Enzymes
UniProtKB help_outline | 6,564 proteins |
Enzyme class help_outline |
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- Name help_outline L-aspartate Identifier CHEBI:29991 Charge -1 Formula C4H6NO4 InChIKeyhelp_outline CKLJMWTZIZZHCS-REOHCLBHSA-M SMILEShelp_outline [NH3+][C@@H](CC([O-])=O)C([O-])=O 2D coordinates Mol file for the small molecule Search links Involved in 75 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline fumarate Identifier CHEBI:29806 (CAS: 142-42-7) help_outline Charge -2 Formula C4H2O4 InChIKeyhelp_outline VZCYOOQTPOCHFL-OWOJBTEDSA-L SMILEShelp_outline [O-]C(=O)\C=C\C([O-])=O 2D coordinates Mol file for the small molecule Search links Involved in 41 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline NH4+ Identifier CHEBI:28938 (CAS: 14798-03-9) help_outline Charge 1 Formula H4N InChIKeyhelp_outline QGZKDVFQNNGYKY-UHFFFAOYSA-O SMILEShelp_outline [H][N+]([H])([H])[H] 2D coordinates Mol file for the small molecule Search links Involved in 529 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
RHEA:16601 | RHEA:16602 | RHEA:16603 | RHEA:16604 | |
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Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
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Publications
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Studies on aspartase. I. Purification and molecular properties of aspartase from Escherichia coli.
Suzuki S., Yamaguchi J., Tokushige M.
Biochim. Biophys. Acta 321:369-381(1973) [PubMed] [EuropePMC]
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L-aspartase from Escherichia coli: substrate specificity and role of divalent metal ions.
Falzone C.J., Karsten W.E., Conley J.D., Viola R.E.
The enzyme L-aspartase from Escherichia coli has an absolute specificity for its amino acid substrate. An examination of a wide range of structural analogues of L-aspartic acid did not uncover any alternate substrates for this enzyme. A large number of competitive inhibitors of the enzyme have bee ... >> More
The enzyme L-aspartase from Escherichia coli has an absolute specificity for its amino acid substrate. An examination of a wide range of structural analogues of L-aspartic acid did not uncover any alternate substrates for this enzyme. A large number of competitive inhibitors of the enzyme have been characterized, with inhibition constants ranging over 2 orders of magnitude. A divalent metal ion is required for enzyme activity above pH 7, and this requirement is met by many transition and alkali earth metals. The binding stoichiometry has been established to be one metal ion bound per subunit. Paramagnetic relaxation studies have shown that the divalent metal ion binds at the recently discovered activator site on L-aspartase and not at the enzyme active site. Enzyme activators are bound within 5 A of the enzyme-bound divalent metal ion. The activator site is remote from the active site of the enzyme, since the relaxation of inhibitors that bind at the active site is not affected by paramagnetic metal ions bound at the activator site. << Less
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Kinetic studies of L-aspartase from Escherichia coli: pH-dependent activity changes.
Karsten W.E., Viola R.E.
The pH dependence of the kinetic parameters of the L-aspartase-catalyzed reaction have been examined in both the amination and the deamination directions. The enzyme isolated from Escherichia coli exists in a pH-dependent equilibrium between a higher pH form that has an absolute requirement for a ... >> More
The pH dependence of the kinetic parameters of the L-aspartase-catalyzed reaction have been examined in both the amination and the deamination directions. The enzyme isolated from Escherichia coli exists in a pH-dependent equilibrium between a higher pH form that has an absolute requirement for a divalent metal ion and for substrate activation, and a low pH form that does not require activation by either substrate or metal ions. The interconversion between these enzyme forms is observed near neutral pH in the profiles examined for the reaction in either direction. This pH-dependent activation has not been observed for other bacterial aspartases. Loss of activity is observed at high pH with a pK value of 9. The pH profiles of competitive inhibitors such as 3-nitropropionic acid and succinic acid have shown that the enzyme group responsible for this activity loss must be protonated for substrate binding at the active site. An enzymatic group has also been identified that must be protonated in the amination reaction, with a pK value near 6.5, and deprotonated in the deamination reaction. This group, tentatively assigned as a histidyl residue, fulfills the criteria for the acid-base catalyst at the active site of L-aspartase. << Less
Arch. Biochem. Biophys. 287:60-67(1991) [PubMed] [EuropePMC]